Papers by Hemn Younesiraad
Study of Parallel-Plate Waveguides Bordered by Reactive Huygens Metasurfaces
IEEE Transactions on Antennas and Propagation
In this paper, we investigate the electromagnetic response of metasurfaces due to excitation of t... more In this paper, we investigate the electromagnetic response of metasurfaces due to excitation of the toroidal moment. An all-dielectric curved metasurface analyzad using a novel theoretical solution based on the Fourier analysis to evaluate the localized fields. Analyzing localized near-field interactions are crucial in investigating the excited trapped modes and enables us to optimize the reflection properties of the proposed metasurface. Optimization is accomplished using graphene layer and resulted a hybrid dielectric-graphene structure with near-zero reflection properties.
─ In this paper, by using improved simplified composite right and left handed transmission lines ... more ─ In this paper, by using improved simplified composite right and left handed transmission lines (I-S-CRLH-TL), a novel 4-way parallel Wilkinson power divider (WPD) is presented. The proposed WPD exhibits the benefits of excellent isolation and equal power split between output ports in the dual frequency band. Also, the dual-band nature of this divider, low cost and easy integration with printed circuits and printed antennas in a compact size makes this device a very good candidate for feeding dual-band antennas and microwave devices. The proposed divider is designed and fabricated on a low cost substrate with permittivity of 4.4 and thickness of 0.79 mm to work at two arbitrary frequency bands of 0.95 GHz and 2.43 GHz. There is a good agreement between simulated and measured results in all cases. The design concept of this paper can be easily extended to another type of dual-band microwave components. Index Terms ─ Dual-band, metamaterial, Wilkinson power divider.
Highly-Efficient Double-Sided Dual-Band Polarization-Independent Metasurface Energy Harvester
2020 28th Iranian Conference on Electrical Engineering (ICEE), 2020
In this paper, a novel highly-efficient dual-sided metasurface harvester is proposed. As an ambie... more In this paper, a novel highly-efficient dual-sided metasurface harvester is proposed. As an ambient energy harvester, the proposed structure absorbs the incident energy on two sides at two frequency bands. The top and bottom metasurfaces are formed by sub-wavelength Jerusalem cells and a symmetric ELC resonator, respectively. The proposed energy harvester is polarization-independent. As a result of two-side topology, the proposed structure incorporates four layers of low-loss substrates. The absorbed energy transfers to the input ports of the corresponding feeding network through the optimally positioned vias under the top and bottom harvesters. Simulations indicate excellent harvesting efficiencies of 94% and 93% calculated at 5.5 GHz and 7.2 GHz, for the top and bottom harvesters, respectively.
Invisibility Utilizing Huygens’ Metasurface Based on Mantle Cloak and Scattering Suppression Phenomen
IEEE Transactions on Antennas and Propagation
This communication presents the design of a Huygens’ metasurface (HMS) coating aiming to achieve ... more This communication presents the design of a Huygens’ metasurface (HMS) coating aiming to achieve strongly enhanced invisibility. An analytical formulation for obtaining the required electric surface admittance and magnetic surface impedance is presented. The proposed unit cell consists of a pair of split-rin resonators in the top layer and a metal capacitor in the bottom layer of the same substrate. The geometries are properly designed to provide the required electric surface admittance and magnetic surface impedance for maximum scattering reduction at the operational frequency of 4 GHz. The designed HMS is optimized to realize the required electric surface admittance and magnetic surface impedance for remarkable cloaking purposes. Scattering-cross section (SCS) of uncloaked and cloaked conducting cylinders is obtained with CST Microwave Studio simulation which matches the analytical results. The results show robust scattering reduction with considerable bandwidth for the covered cylinder by the HMS. Furthermore, the obtained results with HMS are compared with the results presented in the literature for cloaking with ordinary metasurface. This comparison emphasizes a much better cloaking performance of the HMS. Considerable cloaking obtained in this communication can be applied for invisibility purposes, sensing applications, antenna isolation, radiation blockage reduction in antennas, etc.
IET Microwaves, Antennas & Propagation
Progress In Electromagnetics Research Letters
In this paper, a simple dual-band compact slotted square ring patch antenna has been used as hype... more In this paper, a simple dual-band compact slotted square ring patch antenna has been used as hyperthermia applicators in the treatment of cancerous human cells at superficial depths inside the body. The proposed antenna has the advantages of dual-band (f 1 = 434 MHz and f 2 = 915 MHz) operation and more compact size (124 × 124 mm 2 ) than the current state-of-the-art designs without significant frequency detuning or impedance mismatch which makes it a more suitable choice for local hyperthermia. The proposed antenna provides a suitable specific absorption rate (SAR) penetration profile and shows a good resonance at two designed frequencies. We have optimized the structure so that the SAR level performed by the structure is sufficiently enough so as to meet the IEEE standard requirements for medical applications including hyperthermia. We have simulated and measured the structure with a low-profile substrate (i.e., FR4 substrate with ε r = 4.4 and thickness of 1.6 mm). During the design process, the simplified planar tri-layered tissue model interfaced with a water bolus was used to incorporate the main electrical effects on the antenna. The results validate the proposed antenna design.
Scientific Reports
In this paper, we investigate the possibility of improving efficiency in non-radiative wireless p... more In this paper, we investigate the possibility of improving efficiency in non-radiative wireless power transfer (WPT) using metasurfaces embedded between two current varying coils and present a complete theoretical analysis of this system. We use a point-dipole approximation to calculate the fields of the coils. Based on this method, we obtain closed-form and analytical expressions which would provide basic insights into the possibility of efficiency improvement with metasurface. In our analysis, we use the equivalent two sided surface impedance model to analyze the metasurface and to show for which equivalent surface impedance the WPT efficiency will be maximized at the design frequency. Then, to validate our theory, we perform a full-wave simulation for analyzing a practical WPT system, including two circular loop antennas at 13.56 MHz. We then design a metasurface composed of singlesided CLSRRs to achieve a magnetic lensing based on the calculated equivalent surface impedance. The analytical results and full-wave simulations indicated non-radiative WPT efficiency improvement due to amplifying the near evanescent field which can be achieved through inserting the proposed metasurface. Electricity supply is one of the most important challenges with the increasing expansion of electrical appliances and changes in the human lifestyle. Wireless Power Transfer (WPT) is one of the most useful and practical solutions for charging a variety of electronic devices 1 . The earliest suggestions of WPT were proposed by Tesla in 1891, but his prototype was not safe and practical due to the lack of standard radio frequency technology at that time 2 . Wireless power transfer can be used to charge personal electrical devices (smartphones, tablets, laptops), electric vehicles 3 , medical implanted devices 4,5 and so on. In 1963, the first microwave WPT was demonstrated by Brown 6 . Wireless power systems, mainly fall into two categories: far-field transmission and near-field transmission. In the far-field region or radiative transmission, also called power beaming, power is transferred by beams of electromagnetic radiation, such as microwaves or laser beams. In this type of WPT, the energy is transferred through absorption and scattering in the atmosphere. which requires a direct line of sight between the source and the device . The main challenge in this WPT scheme is human electromagnetic exposure safety and WPT efficiency issues. Radiative WPT is suitable for space or military applications. In the near-filed region or non-radiative WPT, energy is transferred through near-field electromagnetic waves from the source to receiver 9 . In this WPT scheme, the operational distance between the transmitter and receiver is far shorter than the wavelength which is suitable for charging electrical devices with short and midrange distance. In this region, the oscillating electric and magnetic fields are decoupled and power can be transferred via electric near-fields via capacitive coupling (electrostatic induction) 10 between metal electrodes, or via magnetic near-fields by inductive coupling (electromagnetic induction) between coils of the wire 11 . The other type of WPT schemes is magnetic resonant coupling power transfer (MRPT), where the energy can be transferred between two magnetically coupled resonant devices with the same resonance frequency. In 12 , using self-resonance coils in a strongly coupled regime the efficiency of non-radiative WPT over a distance of up to 8 times the radius of the coils has been demonstrated experimentally with about 40% efficiency over a distance of 2 meters. Since in the near field of magnetic dipole antennas the E/H ratio can be strongly
A novel fully planar quad band Wilkinson power divider
AEU - International Journal of Electronics and Communications, 2017
Abstract In this paper, by using extended composite right and left handed transmission line (E-CR... more Abstract In this paper, by using extended composite right and left handed transmission line (E-CRLH-TL), the fully planar quad band Wilkinson power divider (WPD) proposed exhibits the benefits of bandwidth enlargement, excellent isolation and equal power split between output ports in the four pass-bands. The proposed divider is designed and fabricated on a low cost substrate with dielectric constant of 4.4 and a thickness of 0.8 mm as work at four arbitrary frequency bands of 2.4 GHz (ISM), 3.5 GHz (WiMax), 5.2 GHz (WiFi) and 5.8 GHz (WiFi). The results of the measured and simulated designs are in good agreement with each other which verifies the proposed design methodology. The design concept of this paper can be easily extended to various multi-band microwave devices.
Small Multi-Band Rectangular Dielectric Resonator Antennas for Personal Communication Devices
International Journal of Electrical and Computer Engineering (IJECE), 2014
The design of a novel rectangular dielectric resonator antenna (DRA) for multi-band application h... more The design of a novel rectangular dielectric resonator antenna (DRA) for multi-band application has been presented in this paper. The presented antenna has been composed of very low cost and relatively low dielectric constant substrate materials while three-segment thin dielectrics with different sizes have been used and separated by two metal plates in order to set the four different frequency bands. The proposed quad-band antenna operates at 2.4/3.5/5.2 & 5.8 GHz. The radiation pattern, gain and VSWR of this antenna show very good operation for this antenna in all frequency bands. The first method based on finite element method (FEM) and the second one based on finite integral technique (FIT) have been used to analyze antenna structure, and subsequently the Genetic Algorithm (GA) has been applied by using HFSS simulator to obtain the optimized parameters. DOI: http://dx.doi.org/10.11591/ijece.v4i1.4576
A Novel Small Triple Band Rectangular Dielectric Resonator Antenna for WLAN and WiMAX Applications
Journal of Electromagnetic Waves and Applications, 2011
ABSTRACT A novel triple band rectangular dielectric resonator antenna is presented for satisfying... more ABSTRACT A novel triple band rectangular dielectric resonator antenna is presented for satisfying wireless local area network (WLAN) and worldwide interoperability for microwave access (WiMAX) applications simultaneously. The proposed triple-band antenna operates at 2.4 GHz/3.5 GHz/5.8 GHz. By using three plexiglass dielectrics on FR4 board, a very low cost antenna is designed. In addition, a modified version of the rectangular dielectric resonator antenna, which has three-segment thin dielectrics with different sizes, provides omnidirectional radiation over the frequency bands. The antenna is fabricated, and a good agreement is achieved between the simulated and measured results. The designed triple-band antenna with extremely low cost and low profile is very suitable for multiband mobile communication systems. To the authors' knowledge, this is the first triple band dielectric resonator antennas (DRAs) presented with stable radiation patterns (nearly omnidirectional pattern) for each operating band.
IEEE Access
In this paper, we investigate the electromagnetic response of a Huygens' metasurface (HMS) embedd... more In this paper, we investigate the electromagnetic response of a Huygens' metasurface (HMS) embedded between the transmitter and receiver coils of a near field wireless power transfer (WPT) system and their interactions for the feasibility of increasing efficiency. To analyze the proposed configuration, we use the point-dipole approximation to describe the electromagnetic fields and boundary conditions governing HMS to calculate the mutual inductance between the coils and to obtain closed-form analytical expressions. The proposed theory shows that by optimally designing the HMS inclusions, the amplitude of the mutual inductance between the transmitter and receiver coils in the near-field WPT can be increased, resulting in improved efficiency. Finally, by drawing on the proposed theory, we design a thin layer and finite-size HMS consisting of 64 elements. The bianisotropic Omega-type particle is used to design the HMS to improve the efficiency of the sample WPT system at the frequency of 100 MHz. The results of the full-wave simulation show that the power transfer efficiency in the free space increases from 25% to 42% in the presence of the proposed HMS. INDEX TERMS Wireless power transfer, Huygens metasurfaces, power transfer efficiency.
IET Microwaves, Antennas & Propagation
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Papers by Hemn Younesiraad